This invention relates to blends of an aromatic polycarbonate or polyestercarbonate with a 4-methyl-1-pentene polymer.
Blends of polycarbonate with a variety of polyolefins are described in the prior art. U.S. Pat. No. 3,431,224 discloses blends of polyethylene, polypropylene, polyisobutylene, a copolymer of ethylene and an alkyl acrylate or a copolymer of ethylene and propylene. U.S. Pat. No. 3,477,978 describes blends of an aromatic polycarbonate with a polymer of an olefin of 2-3 carbon atoms. Protective body armor fabricated from a polycarbonate and 3 to 7 percent of a polyolefin is claimed in U.S. Pat. No. 3,437,631. A process for preparing a blend of an olefin polymer and a polycarbonate is described in U.S. Pat. No. 3,801,673.
U.S. Pat. No. 4,245,058 teaches that ternary blends of aromatic polycarbonates, an acrylate copolymer and a polyolefin are thermoplastic compositions possessing improved impact strength. The polycarbonates employed in these blends also can contain ester moieties. The Japanese Patent Application No. 55-090,550, published July 9, 1980, also describes blends of polyestercarbonates and certain polyolefins.
The prior art blends of polycarbonate and polyolefin exhibit some improvement in impact strength relative to polycarbonate alone, particularly at below ambient temperatures of after exposure to high temperatures. However, relatively little improvement is imparted by these blends in the capacity of the thermoplastic to withstand exposure to organic solvents without failure under stress. This property is frequently referred to as "environmental stress crack resistance". The Izod impact strength of these blends also declines following extended exposure to water. Accordingly, it would be desirable to identify blends of polycarbonates which exhibit greater environmental stress crack resistance and improved strength after exposure to water.